Human secretory leukocyte protease inhibitor (SLPI); a serine protease
inhibitor found concentrated in secretory fluids, has been postulated
to participate in the body's natural defense against infection by the
human immunodeficiency virus type-1 (HIV-1) by affecting trypsin-like
enzymes on the surface of target cells. SLPI was evaluated for potent
ial antiviral activity against laboratory, clinical and monocytotropic
strains of HIV-1 in human T-cell lines, peripheral blood lymphocytes
and monocyte/macrophage cultures. SLPI was tested in a single cycle of
infection assay and under conditions in which SLPI was preincubated b
oth with target cells and with virus and then maintained during the vi
rus-to-cell adsorption phase and throughout the entire culture period.
However, SLPI did not exert anti-HIV activity under any experimental
conditions; and mechanistic studies showed SLPI to have no inhibitory
activity on HIV-1 binding, reverse transcriptase or protease. Thus, SL
PI exhibited no suggestive anti-HIV-1 activity.